Slides in this set

Slide 1

Slide 2

Atoms and RadioactivityAtoms: Mass&charge: Proton: 1 + Carbon 12 atom. Atomic number 6 Neutron 1 o (protons), mass number 12 (protons + Electron - neutrons).Ionising Radiation: Alpha ­ helium nuclei ejected from unstable nuclei. Very ionising but only short range, stopped by thin card. Beta ­ fast moving elections ejected from unstable nuclei (neutron breaks down to proton and electron). Less ionising, longer range, stopped by 1-2mm of aluminium. Gamma rays ­ electromagnetic photons. Not very ionising but extremely penetrating and can only be stopped by thick lead. Massless and without charge.Nuclear transformations: Some radioactive isotopes will decay randomly over time, emitting combinations of radiation.…read more

Slide 3

Examples of radioactive decay Each of these reactions will also give off energy as a bi-product. After an alpha or beta particle has been emitted any surplus energy is emitted as gamma radiation. These are pure energy and there is no change to the atomic or mass number or the atom that emits this.…read more

Slide 4

RadiationDetecting radiation: Background radiation: Photographic film ­ We are constantly exposed to becomes fogged when radiation from different natural exposed to ionising and man made sources. radiation, used in badges for workers at risk from exposure and checked regularly to ensure safety limits have not been exceeded. Geiger-Muller tube ­ ionising radiation in the tube ionises the gases within, allowing a pulse of current to pass between the electrodes. This reaches a counter which clicks when it detects the radiation.…read more

Slide 5

Half LifeRadioactive decay: The half-life t1/2 , of a Random process radioactive isotope is the However you can predict time taken for half the how many atoms will decay original number of nuclei to in a time. decay. Decay rate measured in Bq, The half life of each decays per second. particular radioactive isotope does not change, As decaying proceeds the however different isotopes number of unstable nuclei have very different half lives. decreases, as does the rate of decay. The proportion of decaying Decay rate, Bq material stays the same. t1/2 Time, t…read more

Slide 6

Applications of radioactivity Medicine ­ used for x-rays, Hazards of radioactivity: to kill cancer and other It can kill cells, with a high illnesses. dose at areas performing Sterilisation ­ kills of critical functions it can be microorganisms and fatal. bacteria on surgical It can also effect genetic equipment and some food. material of a cell, making it Radioactive dating ­ by mutate. measuring the proportion of Workers in the nuclear carbon-14 (radioactive) in industry wear the badges to organic material as it decays ensure they aren't exposed at a predictable rate. You can to strong ionising radiation. tell roughly how long the Fission reactors produce a material has been dead. variety of waste that needs Some inorganic materials to be safely enclosed in lead can also be dated. or concrete.…read more